1. Field of the Invention
This invention relates to a projection apparatus, a projection method, and a medium.
2. Description of the Related Art
Jpn. Pat. Appln. KOKAI Publication No. 2003-280087 (patent document) has disclosed the technique for blanking a projected picture temporarily while adjusting the output luminance of the light source lamp without turning off the lamp during projection.
The technique described in the above patent document has taken into account the starting characteristic of an ultrahigh-pressure mercury lamp used as a light source lamp, that is, the time required for the lamp to light up again once the lamp has gone out.
Therefore, the output luminance of the light source lamp is adjusted according to two states, the display and nondisplay of a picture. When a picture is muted, the image is, of course, brought into the nondisplay state to stop displaying the entire projected picture.
With the recent popularization of personal computers (PCs), it is commonplace to connect a PC to a projection unit and make a presentation.
In this type of presentation, it is highly likely that pictures will be projected using, for example, a whiteboard as a screen, not a special screen. In that case, the whiteboard functions not only as a screen but also as a whiteboard on which various types of information, including questions, suggestions, and points related to the presentation, are written with a marker pen.
When the whiteboard is used as a screen, with a large part of the whiteboard being occupied only by the projection region because the area of the whiteboard is small, there is no space in which characters or the like are to be written. Therefore, characters or the like have to be written into the projection region. Since what has been written overlaps with what has been projected, it is very difficult to read what has been written.